Little is known about the sleep of shift workers. The research program proposed will examine the effects of shift work on the laboratory sleep of industrial workers using electrophysiological measures. Both sleep-stage and averaged evoked brain response measurements of sleep will be studied. Appropriate measurements of body temperature, urinary excretion, personality factors, and vigilance performance will also be made. The influence of job duties, work shift, and work shift experience on these measurements will be examined to determine the relation of these factors to the health and safety of industrial workers.